Nice fix!
This is more clear and robust.
Extra memory allocation is Ok.
Thanks,
Serguei
On 3/7/13 3:54 AM, Staffan Larsen wrote:
> Here is a webrev for fixing this problem. I actually removed all of
> our own tokenization code in dll_build_name() and replaced it with
> calls to strtok_r (strtok_s on windows) instead. I think this should
> be more robust, at the cost of an extra memory allocation. I've also
> added the const qualifier to some of the parameters.
>>http://cr.openjdk.java.net/~sla/8009558/webrev.02/> <http://cr.openjdk.java.net/%7Esla/8009558/webrev.02/>
>> All of the jdi and hprof tests passes with this change.
>> Thanks,
> /Staffan
>> On 6 mar 2013, at 20:48, serguei.spitsyn at oracle.com> <mailto:serguei.spitsyn at oracle.com> wrote:
>>> Staffan,
>>>> Thank you for the confirmation and taking care about this issue!
>>>> Thanks,
>> Serguei
>>>>>> On 3/6/13 11:36 AM, Staffan Larsen wrote:
>>> Nice catch, Serguei!
>>>>>> Unfortunately I have already pushed my change, but I filed
>>> "JDK-8009558: linked_md.c::dll_build_name can get stuck in an
>>> infinite loop" to track this new problem and I am working on a fix.
>>>>>> Thanks,
>>> /Staffan
>>>>>>>>> On 5 mar 2013, at 20:26, serguei.spitsyn at oracle.com>>> <mailto:serguei.spitsyn at oracle.com> wrote:
>>>>>>> Hi Staffan,
>>>>>>>> Thank you for this discovery!
>>>> It looks good, but I have a couple of comments.
>>>>>>>> It seems, there is one more problem in this code:
>>>> 68 /* check for NULL path */
>>>> 69 if (p == pathname) {
>>>> 70 continue;<== Endless loop if we hit this line
>>>> 71 }
>>>>>>>> Do we need to do 'pathname++' before continuing at the line #70?
>>>> It is going to be endless loop in cases there is a PATH_SEPARATOR
>>>> at the beginning of paths or two PATH_SEPARATOR's in a row.
>>>> These would be incorrect path lists but the code above is targeting
>>>> exactly such cases.
>>>>>>>> Also, the argument name "pathname" in the original code is confusing.
>>>> Should we rename it to "pathnames"?
>>>>>>>> Thanks,
>>>> Serguei
>>>>>>>>>>>> On 3/4/13 10:56 AM, Staffan Larsen wrote:
>>>>> I accidentally stepped on this bug the other day. There is a problem in linker_md.c : dll_build_name() where an internal pointer can be moved to point outside the string. The code looks like:
>>>>>>>>>> 57 static void dll_build_name(char* buffer, size_t buflen,
>>>>> 58 const char* pname, const char* fname) {
>>>>> 59 // Based on os_solaris.cpp
>>>>> 60
>>>>> 61 char *path_sep = PATH_SEPARATOR;
>>>>> 62 char *pathname = (char *)pname;
>>>>> 63 while (strlen(pathname) > 0) {
>>>>> 64 char *p = strchr(pathname, *path_sep);
>>>>> 65 if (p == NULL) {
>>>>> 66 p = pathname + strlen(pathname);
>>>>> 67 }
>>>>> 68 /* check for NULL path */
>>>>> 69 if (p == pathname) {
>>>>> 70 continue;
>>>>> 71 }
>>>>> 72 (void)snprintf(buffer, buflen, "%.*s/lib%s." LIB_SUFFIX, (p - pathname),
>>>>> 73 pathname, fname);
>>>>> 74
>>>>> 75 if (access(buffer, F_OK) == 0) {
>>>>> 76 break;
>>>>> 77 }
>>>>> 78 pathname = p + 1;
>>>>> 79 *buffer = '\0';
>>>>> 80 }
>>>>>>>>>> If the supplied pname is a buffer with a simple path without any path separators in it, p will be set to the terminating nul on line 66. Then on line 78 it will be moved outside the buffer. Fixing this also necessitates fixes to the callers to check for an empty return string (in buffer).
>>>>>>>>>> The same code show up in both the solaris code and the windows code as well as hprof.
>>>>>>>>>> bug:http://bugs.sun.com/view_bug.do?bug_id=8009397>>>>> webrev:http://cr.openjdk.java.net/~sla/8009397/webrev.00/>>>>>>>>>> Thanks,
>>>>> /Staffan
>>>>>>>>>>